Peptide

LL-37

Also known as

Cathelicidin LL-37 · Cathelicidin antimicrobial peptide · hCAP-18 fragment · CAP-18 C-terminal peptide · hCAP18-derived peptide · Ropocamptide (investigational topical designation / Promore Pharma) · LL37 · LL 37 · Human cathelicidin · FALL-39 (historical related designation talk)

Community talk. May contain inaccuracies. Not medical advice. Not a protocol. Not for human or animal use.

What it is

Human defense peptide	LL-37 is a human antimicrobial and immune-signaling peptide discussed for persistent infections, gut symptoms and wound healing.
Route changes the evidence	Topical wound gel, called ropocamptide in development, is different from community injections beneath the skin. Gel concentrations cannot supply an equivalent injection amount.

Notes

LL-37 is a human defense peptide that people discuss for persistent infections, gut symptoms and wound healing. Injectable reports include perceived improvement, incomplete relief and substantial worsening. Feeling feverish or calling a reaction ‘die-off’ does not show that an infection is clearing.

Antimicrobial and immune signaling are different jobs. ‘Biofilm-busting’ means disrupting protective communities microbes form. Posters connect laboratory activity with Lyme, mold-associated symptoms, sinus problems and SIBO, bacterial overgrowth in the small intestine. That rationale does not demonstrate clearance in a person. r/SIBO — LL-37 Peptide to kill SIBO? (Community discussion · Accessed 2026-09-30)

Topical wound gel and injected peptide are different exposures. Ropocamptide is the investigational topical designation. Community charts usually describe SubQ, injection beneath the skin. Oral and near-wound discussions have less clearly documented use. Trial gel concentrations cannot be converted into an equivalent injection. Mahlapuu et al. — Evaluation of LL-37 in hard-to-heal venous leg ulcers (2021) (Official context · Accessed 2026-09-30)

Source context — r/SIBO — LL-37 Peptide to kill SIBO?: Theory and non-use, not an LL-37 null trial. Friend's protocol and self-described diagnoses unverified; unrelated reply amounts excluded.

Source context — Mahlapuu et al. — Evaluation of LL-37 in hard-to-heal venous leg ulcers (2021): Sponsor-funded local formulation with compression care; no systemic infection or injection comparison.

What people notice

Gut or infection-symptom relief	Some describe better digestion or partial Lyme-symptom relief without cure. Others stop after substantial worsening; these accounts do not establish infection clearance.
Topical wound results are mixed	The 2021 leg-ulcer gel trial found no significant overall healing advantage, with a later larger-ulcer subgroup signal. That does not validate systemic-injection claims.

Notes

Less digestive discomfort or fewer infection-related symptoms. Gut comfort, easier food tolerance and lower infection ‘load’ are community goals. A Lyme user described partial improvement without cure. These different outcomes do not establish a single ‘immune boost’ effect. r/Lyme — Anyone try LL-37 (Cathelicidin) peptides? (Community discussion · Accessed 2026-09-30)

Better digestion and severe worsening appear in the same discussion. One Phoenix Rising user claims lasting digestive relief after earlier treatment; another stopped after severe worsening within four to five days. Neither establishes a success rate or reason to retry after a crash. Phoenix Rising — LL-37 peptide, page 2 (Community discussion · Accessed 2026-09-30)

Wound healing has route-specific, mixed trial results. The 2021 topical leg-ulcer trial found no significant overall healing advantage over placebo. A later analysis suggested benefit in larger ulcers. That result cannot validate injection stories about systemic infections. Mahlapuu et al. — Evaluation of LL-37 in hard-to-heal venous leg ulcers (2021) (Official context · Accessed 2026-09-30)

Source context — r/Lyme — Anyone try LL-37 (Cathelicidin) peptides?: Repeated replies by the same author are one account. Unverified diagnoses/products; amounts and route unclear. Relative reply dates retained without converting to calendar dates.

Source context — Phoenix Rising — LL-37 peptide, page 2: Self-reports and seller advice; earlier treatments confound response. Family account is secondhand. No clearance measurement.

Doses people talk about

SubQ community charts	Roughly 100–250 mcg total daily recurs, including 125 mcg once daily and a 100–200 mcg/day band. Other charts begin at 50–100 mcg; none establishes tolerability.
Personal versus suggested amount	A Phoenix Rising user reported 100 mcg SubQ once daily, separately from a seller/researcher suggestion of 100 mcg twice daily: 200 mcg/day.
Route-unspecified reports	One Lyme recollection vaguely gives 125 mcg/day; its '5 mg cycle' is a course total. A different adverse account reports 200 mcg/day before a delayed reaction.
Wider competing charts	Separate charts span 50–400 mcg/day or reach 500 mcg/day, using daily, five-on/two-off or every-other-day patterns. These are not safe ceilings.

Notes

SubQ charts: roughly 100–250 mcg total daily. The original community record includes 125 mcg once daily and a conservative 100–200 mcg/day band. Some charts instead begin at 50–100 mcg or describe 50-mcg weekly increases. Those chart conventions do not establish tolerability.

A first-person SubQ report: 100 mcg once daily. The Phoenix Rising author distinguished personal use from a seller/researcher suggestion of 100 mcg twice daily: 200 mcg/day. Phoenix Rising — LL-37 peptide, page 2 (Community discussion · Accessed 2026-09-30)

125 mcg/day recollection; 200 mcg/day adverse report. The Lyme recollection is explicitly uncertain; its ‘5 mg cycle’ means course total. Peptide Critic includes 200 mcg/day before a delayed reaction. Neither stated a route. r/Lyme — Any experience with LL-37 peptide? (Community discussion · Accessed 2026-09-30) · Peptide Critic — LL-37 interested in experiences and feedback (Personal report · Accessed 2026-09-30)

Other charts span 50–400 mcg/day or reach 500 mcg/day. These separate educational/clinic-style ranges are not safe ceilings. Daily, five-days-on/two-off and every-other-day schedules appear. Morning placement and occasional body-weight calculations remain lore rather than measured exposure rules.

Source context — Phoenix Rising — LL-37 peptide, page 2: Self-reports and seller advice; earlier treatments confound response. Family account is secondhand. No clearance measurement.

Source context — r/Lyme — Any experience with LL-37 peptide?: Same-author recollections disagree; no route or objective efficacy established. Cancer-protection and live-blood interpretations are unverified. No sourcing replies used; visible relative dates not converted.

Source context — Peptide Critic — LL-37 interested in experiences and feedback: Page carries deleted-topic notice but reply text was returned publicly. Dates absent; route and medical diagnosis unverified. Vendor/giveaway links present.

Half-life, onset & duration

Felt onset	A dependable benefit onset is unknown. Unwanted reactions appeared within 24 hours, after several doses or weeks into use in different accounts.
Felt duration	No reliable single-dose benefit window emerges. Flu-like symptoms lasted 3–4 days in one account; local burning lasted hours in another, while hives and swelling lasted weeks in a separate report.
Half-life	The app's 0.5-hour value is a modeling assumption. The retained 242 ± 45 minutes concerns stability in mouse plasma outside the body; neither measures human SubQ elimination.

Notes

Reactions can start within a day or after several doses. A 125-mcg account described abdominal pain within 24 hours; route/frequency were unstated. Lyme replies describe early flu-like symptoms; the Peptide Critic reaction began weeks into use. These adverse onsets do not establish a dependable benefit-onset window. r/Peptides — LL-37 and SIBO? (Personal report · Accessed 2026-09-30) · r/Lyme — Anyone try LL-37 (Cathelicidin) peptides? (Community discussion · Accessed 2026-09-30) · Peptide Critic — LL-37 interested in experiences and feedback (Personal report · Accessed 2026-09-30)

No reliable single-dose benefit duration emerges. A Lyme user described recurrence off treatment after partial benefit. Original notes include residual improvement and rebound. Repeated-use stories cannot establish how long one administration acts. r/Lyme — Anyone try LL-37 (Cathelicidin) peptides? (Community discussion · Accessed 2026-09-30)

Adverse symptoms have their own duration. A Lyme account describes three to four flu-like days; HealingWell includes local burning for hours; Peptide Critic describes hives/swelling for weeks. Original local-reaction notes mention 24–48 hours. None measures biological half-life. r/Lyme — Anyone try LL-37 (Cathelicidin) peptides? (Community discussion · Accessed 2026-09-30) · HealingWell — Best peptide therapy for lyme? (Community discussion · Accessed 2026-09-30) · Peptide Critic — LL-37 interested in experiences and feedback (Personal report · Accessed 2026-09-30)

0.5 hours is a tracking-app assumption, not a human measurement. BioHack Track uses it to draw an estimated decay curve, without a cited human SubQ measurement. Its commercial model is not a verified clearance value. Half-life describes decline in a measured amount, not symptom relief. BioHack Track — LL-37 reference and model assumption (Community guide · Accessed 2026-09-30)

242 ± 45 minutes in the original note is mouse-plasma stability. The measurement came from plasma incubated outside an animal, not human SubQ elimination. The value is retained from the earlier source review; the later review could not reopen the full text. It does not validate the app estimate or a human interval. Preserved LL-37 mouse-plasma incubation locator (2019) (Animal context · Accessed 2026-09-30)

Source context — r/Peptides — LL-37 and SIBO?: Route/frequency unstated; suspected SIBO and attribution unverified. Comment speculation is not laboratory evidence.

Source context — HealingWell — Best peptide therapy for lyme?: Co-treatment; no amount given. Antibiotic and other-peptide effects cannot be assigned to LL-37.

Source context — BioHack Track — LL-37 reference and model assumption: Promotes an app; no named clinician or specific human clearance citation supports the model. Not an experience report.

Source context — Preserved LL-37 mouse-plasma incubation locator (2019): Fresh PMC/Europe PMC/BioC access failed. Exact value preserved from original; no fresh full-text verification or human PK inference claimed.

Cycles people discuss

Short-course charts	Charts include 2–3 weeks on with at least 2 off, or 4 weeks on with 2–4 off. These breaks are informal calendars, not validated washouts.
Longer personal histories	Accounts include 6 weeks on/2 off/6 on, roughly 30 on/30 off and stopping after 3–4 months. One Lyme history gives conflicting six-month and one-year recollections.
Other long charts	125 mcg daily for about 50 days then 4 weeks off, and 8–12-week courses appear in vendor or clinic-style charts. Repeat-course safety is unresolved.

Notes

Original short-course charts: 2–3 weeks on, at least 2 off; or 4 on, 2–4 off. A four-weeks-on/two-off repeated-block chart also appears. These are informal calendars, not validated washout periods or evidence that repeating a course is safe.

Actual accounts include 6 weeks on/2 off/6 on and roughly 30 on/30 off. The first is a digestive account. The Lyme recollection also describes months between courses and conflicting six-month versus one-year histories. Another Lyme user stopped after three to four months. Phoenix Rising — LL-37 peptide, page 2 (Community discussion · Accessed 2026-09-30) · r/Lyme — Any experience with LL-37 peptide? (Community discussion · Accessed 2026-09-30) · r/Lyme — Anyone try LL-37 (Cathelicidin) peptides? (Community discussion · Accessed 2026-09-30)

Longer chart claims: 125 mcg daily for about 50 days, then 4 weeks off; or 8–12-week courses. These vendor/clinic-style conventions remain separate from shorter blocks. Off-period arguments focus on inflammation and uncertain long-term exposure, not demonstrated human clearance.

Source context — Phoenix Rising — LL-37 peptide, page 2: Self-reports and seller advice; earlier treatments confound response. Family account is secondhand. No clearance measurement.

Stacks

TA1 and KPV	LL-37 plus thymosin alpha-1, sometimes with KPV, appears in immune and gut discussion. Adding TA1 has not been shown here to cancel LL-37 risks.
Repair and infection regimens	BPC-157, TB-500 and GHK-Cu appear alongside LL-37. Herbs, antibiotics, infusions, probiotics and wound care also share credit; immune blends have no universal ratio.

Notes

Immune “defense trio” (very common clinic/forum cluster): LL-37 + Thymosin Alpha-1 + KPV — framed as antimicrobial (LL-37) + immune modulation (TA1) + inflammation calm (KPV); multi-agent confounds dominate outcome stories. [community]

LL-37 + Thymosin Alpha-1 (without KPV): Infection/immune forum pairing when people want antimicrobial + T-cell/innate support narratives without the anti-inflammatory fragment. [community]

Gut / barrier talk: Sometimes with KPV (and/or BPC-157) in GI and “leaky gut + bug load” threads — attribution is murky. [community]

A research label does not verify contents or safety. FDA flags possible immune reactions and peptide impurities, insufficient human safety information, and nonclinical reproductive and tissue-specific tumor concerns. These are reasons for caution, not a quantified personal cancer risk. Adding TA1 has not been shown here to cancel them. FDA — Compounding substances that may present significant safety risks (Official context · Accessed 2026-09-30) · r/Lyme — Any experience with LL-37 peptide? (Community discussion · Accessed 2026-09-30)

SIBO questions are not automatically treatment outcomes. An r/SIBO questioner confirmed non-use. Another thread has an LL-37-positive reply involving GLOW, probiotics and later peptides; the opening post describes a different regimen. Recalled syringe units are not a verified LL-37 dose. r/SIBO — LL-37 Peptide to kill SIBO? (Community discussion · Accessed 2026-09-30) · r/SIBO — Unexpectedly found a cure (peptides), LL-37 reply context (Community discussion · Accessed 2026-09-30)

Stacks blur the result and the amount. TA1/KPV appear in immune talk; BPC-157/TB-500/GHK-Cu in gut/repair stories. Herbs, antibiotics, infusions and wound care confound outcomes. ‘Immune blends’ have no universal ratio. Vitamin-D and inflammation-lab talk does not supply an LL-37 level or prove clearance. r/Lyme — Any experience with LL-37 peptide? (Community discussion · Accessed 2026-09-30)

Source context — FDA — Compounding substances that may present significant safety risks: Risk statement; no quantified human cancer probability or endorsement of a regimen.

Source context — r/SIBO — Unexpectedly found a cure (peptides), LL-37 reply context: Multiple agents, imprecise memories and syringe-unit descriptions. No mass conversion, recipe, verified product or microbiological cure inferred.

Watch for

Worsening is not proof of die-off	Feverishness, abdominal pain, prolonged spasms or a severe crash do not demonstrate microbial killing. 'Herx' is the community's explanation, not a diagnosis.
Hives and facial swelling	One delayed reaction involved weeks of hives and eyelid swelling. New or severe swelling needs medical assessment; breathing difficulty, wheezing or fainting is an emergency.
Immune and product concerns	FDA flags possible immune reactions, peptide impurities and insufficient human safety information, plus nonclinical reproductive and tissue-specific tumor concerns. These are not quantified personal risk rates.

Notes

Worsening is not proof of microbial killing. ‘Herx’ is a community explanation, not a diagnosis. One user reported prolonged muscle spasms after a four-week course; cause/product/amount were unverified. Original discussion flags include psoriasis, rosacea, lupus, pregnancy and immunosuppression, without measured injection-risk rates. r/Peptides — How to undo damage from LL-37? (Personal report · Accessed 2026-09-30)

Hives and facial swelling deserve attention. The poster's self-diagnosis of mast-cell activation is unverified. New or severe swelling needs medical assessment; breathing difficulty, wheezing or fainting is an emergency. Suggestions to add another peptide do not establish treatment. Peptide Critic — LL-37 interested in experiences and feedback (Personal report · Accessed 2026-09-30) · MedlinePlus — Angioedema (Official context · Accessed 2026-09-30)

Source context — r/Peptides — LL-37 and SIBO?: Route/frequency unstated; suspected SIBO and attribution unverified. Comment speculation is not laboratory evidence.

Source context — r/Peptides — How to undo damage from LL-37?: No verified amount, product or causal diagnosis; speculative remedy replies are excluded. Exact publication date not returned in opened body.

Source context — Phoenix Rising — LL-37 peptide, page 2: Self-reports and seller advice; earlier treatments confound response. Family account is secondhand. No clearance measurement.

Source context — HealingWell — Best peptide therapy for lyme?: Co-treatment; no amount given. Antibiotic and other-peptide effects cannot be assigned to LL-37.

Source context — MedlinePlus — Angioedema: General reaction guidance; does not diagnose the forum poster or establish LL-37 causation.

Source context — FDA — Compounding substances that may present significant safety risks: Risk statement; no quantified human cancer probability or endorsement of a regimen.

Full notes

What LL-37 is and why people try it

LL-37 is a 37-amino-acid fragment released from a larger protein called hCAP18. It participates in the body's early response to microbes and tissue injury.

Antimicrobial and immune signaling are different jobs. ‘Biofilm-busting’ means disrupting protective communities microbes form. Posters connect laboratory activity with Lyme, mold-associated symptoms, sinus problems and SIBO, bacterial overgrowth in the small intestine. That rationale does not demonstrate clearance in a person. Reddit r/SIBO Community
Topical wound gel and injected peptide are different exposures. Ropocamptide is the investigational topical designation. Community charts usually describe SubQ, injection beneath the skin. Oral and near-wound discussions have less clearly documented use. Trial gel concentrations cannot be converted into an equivalent injection. Official context Community

Benefits people seek and report

Less digestive discomfort or fewer infection-related symptoms. Gut comfort, easier food tolerance and lower infection ‘load’ are community goals. A Lyme user described partial improvement without cure. These different outcomes do not establish a single ‘immune boost’ effect. Community Reddit r/Lyme
Wound healing has route-specific, mixed trial results. The 2021 topical leg-ulcer trial found no significant overall healing advantage over placebo. A later analysis suggested benefit in larger ulcers. That result cannot validate injection stories about systemic infections. Official context

Doses people discuss

These are descriptions of use and charts, not instructions. mcg means micrograms; 1,000 mcg equals 1 mg.

SubQ charts: roughly 100–250 mcg total daily. The original community record includes 125 mcg once daily and a conservative 100–200 mcg/day band. Some charts instead begin at 50–100 mcg or describe 50-mcg weekly increases. Those chart conventions do not establish tolerability. Community
A first-person SubQ report: 100 mcg once daily. The Phoenix Rising author distinguished personal use from a seller/researcher suggestion of 100 mcg twice daily: 200 mcg/day. Phoenix Rising ME/CFS forum
125 mcg/day recollection; 200 mcg/day adverse report. The Lyme recollection is explicitly uncertain; its ‘5 mg cycle’ means course total. Peptide Critic includes 200 mcg/day before a delayed reaction. Neither stated a route. Reddit r/Lyme Personal report
Other charts span 50–400 mcg/day or reach 500 mcg/day. These separate educational/clinic-style ranges are not safe ceilings. Daily, five-days-on/two-off and every-other-day schedules appear. Morning placement and occasional body-weight calculations remain lore rather than measured exposure rules. Community

Half-life

0.5 hours is a tracking-app assumption, not a human measurement. BioHack Track uses it to draw an estimated decay curve, without a cited human SubQ measurement. Its commercial model is not a verified clearance value. Half-life describes decline in a measured amount, not symptom relief. Community guide

Onset: when people notice something

Reactions can start within a day or after several doses. A 125-mcg account described abdominal pain within 24 hours; route/frequency were unstated. Lyme replies describe early flu-like symptoms; the Peptide Critic reaction began weeks into use. These adverse onsets do not establish a dependable benefit-onset window. Personal report Reddit r/Lyme Personal report

Duration: how long changes last

No reliable single-dose benefit duration emerges. A Lyme user described recurrence off treatment after partial benefit. Original notes include residual improvement and rebound. Repeated-use stories cannot establish how long one administration acts. Reddit r/Lyme Community
Adverse symptoms have their own duration. A Lyme account describes three to four flu-like days; HealingWell includes local burning for hours; Peptide Critic describes hives/swelling for weeks. Original local-reaction notes mention 24–48 hours. None measures biological half-life. Reddit r/Lyme HealingWell Lyme forum Personal report Community

Cycles and time off

Original short-course charts: 2–3 weeks on, at least 2 off; or 4 on, 2–4 off. A four-weeks-on/two-off repeated-block chart also appears. These are informal calendars, not validated washout periods or evidence that repeating a course is safe. Community
Actual accounts include 6 weeks on/2 off/6 on and roughly 30 on/30 off. The first is a digestive account. The Lyme recollection also describes months between courses and conflicting six-month versus one-year histories. Another Lyme user stopped after three to four months. Phoenix Rising ME/CFS forum Reddit r/Lyme Reddit r/Lyme
Longer chart claims: 125 mcg daily for about 50 days, then 4 weeks off; or 8–12-week courses. These vendor/clinic-style conventions remain separate from shorter blocks. Off-period arguments focus on inflammation and uncertain long-term exposure, not demonstrated human clearance. Community

Good to know

Worsening is not proof of microbial killing. ‘Herx’ is a community explanation, not a diagnosis. One user reported prolonged muscle spasms after a four-week course; cause/product/amount were unverified. Original discussion flags include psoriasis, rosacea, lupus, pregnancy and immunosuppression, without measured injection-risk rates. Personal report Community
Hives and facial swelling deserve attention. The poster's self-diagnosis of mast-cell activation is unverified. New or severe swelling needs medical assessment; breathing difficulty, wheezing or fainting is an emergency. Suggestions to add another peptide do not establish treatment. Personal report Official context
A research label does not verify contents or safety. FDA flags possible immune reactions and peptide impurities, insufficient human safety information, and nonclinical reproductive and tissue-specific tumor concerns. These are reasons for caution, not a quantified personal cancer risk. Adding TA1 has not been shown here to cancel them. Official context Reddit r/Lyme

From community discussion

Better digestion and severe worsening appear in the same discussion. One Phoenix Rising user claims lasting digestive relief after earlier treatment; another stopped after severe worsening within four to five days. Neither establishes a success rate or reason to retry after a crash. Phoenix Rising ME/CFS forum
SIBO questions are not automatically treatment outcomes. An r/SIBO questioner confirmed non-use. Another thread has an LL-37-positive reply involving GLOW, probiotics and later peptides; the opening post describes a different regimen. Recalled syringe units are not a verified LL-37 dose. Reddit r/SIBO Reddit r/SIBO
Feeling a strong reaction can leave benefit unresolved. A HealingWell user had joint pain/headaches after five to six weeks and remained unsure of benefit. Lyme accounts include lowering an unspecified amount after early reactions and improvement without clearance. HealingWell Lyme forum Reddit r/Lyme Reddit r/Lyme
Stacks blur the result and the amount. TA1/KPV appear in immune talk; BPC-157/TB-500/GHK-Cu in gut/repair stories. Herbs, antibiotics, infusions and wound care confound outcomes. ‘Immune blends’ have no universal ratio. Vitamin-D and inflammation-lab talk does not supply an LL-37 level or prove clearance. Community Reddit r/Lyme

Supporting context: measurements and route

242 ± 45 minutes in the original note is mouse-plasma stability. The measurement came from plasma incubated outside an animal, not human SubQ elimination. The value is retained from the earlier source review; the later review could not reopen the full text. It does not validate the app estimate or a human interval. Animal context
Topical trial calendars followed wound dressings. The earlier trial used four weeks of twice-weekly applications; the later trial used thirteen weeks. Their local formulations and compression care are separate from community injection cycles. Official context